As a conventional diaphragm pump, a diaphragm pump including a substantially rectangular parallelepiped housing and a stepping motor projecting out from the housing (see e.g., Japanese Unexamined Patent Publication No. 2012-225499). The housing described in Japanese Unexamined Patent Publication No. 2012-225499 includes a housing main body, an upper cover that covers an upper opening of the housing main body, a flow path structural body that covers a lower opening of the housing main body and formed with a flow path that allows liquid to flow therethrough.
The diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499 includes a diaphragm between the housing main body and the flow path structural body, the diaphragm having an annular portion of the outer periphery sandwiched between a bottom portion of the housing main body and an upper portion of the flow path structural body over the entire periphery. The diaphragm opens and closes the flow path formed in the flow path structural body as the central portion moves in a vertical direction.
The diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499 includes a valve shaft extending in the vertical direction and integrally connected to the central portion of the diaphragm and a coil spring that biases the valve shaft toward the lower side in the vertical direction in a space between the housing main body and the upper cover. The valve shaft includes a protrusion projecting out toward the outer peripheral side.
The diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499 includes a swing member in a space between the housing main body and the upper cover, the swing member including a supporting shaft extending in the horizontal direction and rotatably supported by the housing main body, an output portion projecting out toward the outer peripheral side from the supporting shaft to contact the protrusion of the valve shaft from the lower side, and a plate-shaped protrusion projecting out toward a side opposite to the output portion from the supporting shaft.
The diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499 includes a camshaft in a space between the housing main body and the upper cover, the camshaft including a shaft portion extending in parallel to the supporting shaft of the swing member and rotatably supported by the housing main body and a cam portion projecting out toward the outer peripheral side from the shaft portion to contact the plate-shaped protrusion of the swing member from the upper side. The shaft portion is rotationally driven by a stepping motor.
The diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499 may not operate normally if flapping of the camshaft occurs in a direction orthogonal to the extending direction of the camshaft. In the diaphragm pump described in Japanese Unexamined Patent Publication No. 2012-225499, the flapping of the camshaft in the vertical direction is prevented as the housing main body supports the camshaft by a groove portion in which the upper side in the vertical direction is opened and extends in the vertical direction, and the camshaft is pressed by the upper cover from the upper side in the vertical direction of the groove portion with the camshaft supported by the groove portion.